Scientists from the University of Salford have demonstrated that traces of DNA in the ocean can be used to monitor shark populations.
Nearly half of all known shark species are categorized as being “data deficient”, partially because of the expense and difficultly involved in locating them. Currently, researchers rely on baiting, hooking, and filming large fish, but these techniques are time and capital intensive.
Now the University of Salford study, published in the journal Scientific Reports, has proved it is possible to monitor sharks using environmental DNA (eDNA). This method identifies “tracks” of numerous species of shark using a seawater sample.
“It’s just like when detectives do a forensic search of a crime scene, and can locate tissues and cells that contain the DNA of the suspects,” explains Stefano Mariani, professor of conservation genetics at the University of Salford.
The research team took water samples in four sites in the Caribbean and three in the Pacific Coral Sea. They then used a process called metabarcoding to recover shark DNA sequences.
Eleven species were identified in the Bahamas, which proved to be the most diverse site in the Caribbean. In the Pacific, samples from the remote archipelago of Chesterfield contained the largest quantities of shark DNA.
“In order to protect these elusive animals and their ecosystems, we must be able to rapidly assess many areas at repeated time intervals,” says Mariani.
“eDNA should prove a big step forward because basically anyone can collect water samples, and every bottle of water is a potential gold mine of data.”
According to Mariani, the identification method can be made more effective by enhancing molecular tools so every species of interest can be easily identified. More detailed studies are needed to assess the impact of ocean currents in the transfer of shark DNA.